Annular seal, especially for a ball valve

ABSTRACT

In accordance with the invention a sealing ring of deformable material having a radially inwardly facing inner sealing surface and a radially outwardly facing outer sealing surface, characterized by at least one pressure surface which as a wall of a cavity in the sealing ring is in substantially radially opposite relationship to at least one of the sealing surfaces so that a fluid under pressure which bears in the cavity against the pressure surface urges the at least one sealing surface outwardly; and a sealing system comprising a first component with a bore, a second component which is arranged in the bore, and the sealing ring for sealing the gap between the first and the second component in relation to a fluid which at least at times is under pressure.

FIELD OF THE INVENTION

The present invention concerns a sealing ring of deformable materialhaving a radially inwardly facing inner sealing surface and a radiallyoutwardly facing outer sealing surface as well as a sealing systemcomprising a first component with a bore, a second component which isarranged in the bore, and a sealing ring of the specified kind.

BACKGROUND OF THE INVENTION

Seals for sealing off annular gaps are required in technology, inparticular in mechanical engineering, in the most widely varyinggeometrical forms and forms of use. Consequently a wide range ofdifferent design configurations of such seals—also in the form ofpre-prepared standard components, even standardized—are known in thestate of the art. One of the simplest forms of known annular seals is anO-ring of rubber. A so-called shaft sealing ring for example is of asubstantially more complicated configuration, being a sealing elementcomprising a metal ring as an outer seat and a radially inwardly facingsealing lip of rubber.

Shaft sealing rings of that kind serve for example for sealing atransmission casing, out of which a rotating shaft is passed. For thatpurpose the metal ring is seated in a bore in the casing, through whichthe shaft is passed, and the sealing lip bears against acircular-cylindrical peripheral surface of the shaft, that surface beingas smooth as possible. The contact surface between the sealing lip andthe surface of the shaft is reduced to an annular line around theshaft—more specifically by virtue of the fact that the sealing liptapers radially inwardly to form a geometrically sharp edge. Thatconfiguration permits high speeds of rotation of the shaft, in whichcase for example transmission oil which is disposed in the interior ofthe casing and which is to be prevented from escaping from the casing bythe seal forms a lubricating film under the sealing lip. As is known inthat situation dynamic pressure conditions in the region of the contactsurface provide that the oil does not penetrate outwardly by passingthrough beneath the sealing lip.

A further problem in regard to the configuration of the above-describedseals arises out of the fact that the fluid, in relation to which thegap between the two components is to be sealed, is usually under anincreased pressure or a reduced pressure and, as a consequence of thosepressure conditions, a force is exerted on at least one of thecomponents. To carry that force, it is known to arrange additional plainbearings between the first and the second components. Those plainbearings carry the forces exerted by the fluid pressure and provide forgreater ease of mobility as between the two components than if thematerials from which the two components are made were to rub directlyagainst each other.

For structural reasons the plain bearings are usually disposed in theimmediate proximity of the seal. As the plain bearings are frequentlyexposed to wear by virtue of the relative movement of the two componentswith respect to each other, after a certain operating period directcontact can nonetheless occur between the two components, whereby therelative movement of the two components with respect to each other ismade more difficult.

There is also the disadvantage that wear particles from the plainbearing can pass into the region of the seal. That results in increasedwear of the seal and thus regularly causes a deterioration in thesealing action. In addition, even without the seal suffering from wear,deformation of the seal can occur due to migration of wear particlesthrough the sealing gap, and as a consequence a leak can occur.

In addition in particular felt rings are known for sealing annular gapsaround a component which not only rotates but which is also moved with atranslatory motion through the bore.

The effect of known sealing rings is often not sufficient, in particularin relation to fluids which are under pressure, so that unwanted leakagecan occur.

SUMMARY OF THE INVENTION

One object of the invention is to provide a seal and a sealing system,the sealing effect of which is improved over the current systems.

According to the invention that object is attained by a seal having thefeatures of claim 1.

For the purposes of sealing an annular gap between two components asealing ring of deformable, preferably elastically deformable material,for example a polymer, has two sealing surfaces of which faces radiallyinwardly and one faces radially outwardly. Those sealing surfaces thenusually bear against complementary sealing surfaces, for example in asealing groove which is provided suitably in the region of the gap. Inaccordance with the invention the sealing ring is characterized by atleast one pressure surface which is in the form of a wall of a cavity inthe sealing ring. The at least one pressure surface is disposed insubstantially radially opposite relationship to at least one of thesealing surfaces so that a fluid which occurs in the cavity underpressure against the pressure surface urges the at least one sealingsurface outwardly and therefore, upon appropriate installation, againsta complementary sealing surface of a component. The sealing effect issubstantially improved by that pressure, which is increased inaccordance with the invention, of a sealing surface of the sealing ringaccording to the invention. That is particularly advantageous inrelation to annular gaps which are to be sealed off in relation to afluid which is under pressure. In accordance with the invention, in suchan installation situation for the sealing ring according to theinvention, it is possible to make use of the pressure of the fluidinsofar as the sealing ring according to the invention is so installedthat a fluid opening which leads outwardly from the cavity allows thefluid to penetrate into the cavity and there exerts its pressure on thepressure surface and thereby on the radially oppositely disposed sealingsurface.

Preferably the cavity is provided in the sealing ring, in the form of agroove in an axial outside surface of the sealing ring on the peripheryof the sealing ring. Then, particularly when the sealing ring is in theshape of a circular cylindrical tube, the radial boundary surfaces ofthe groove are in opposite relationship to the two sealing surfaces ofthe ring (one facing outwardly and one facing inwardly) and when apressure is applied to the groove by a fluid under pressure, theboundary surfaces urge the sealing surfaces from the cross-section ofthe sealing ring outwardly, that is to say radially outwardly orradially inwardly.

The sealing system according to the invention includes a first componenthaving a bore, a second component arranged in the bore and a sealingring for sealing the gap between the first and second components inrelation to a fluid which at least at times is under pressure. Furtherprovided between the first and second components is a rolling bearingfor carrying axial forces between the two components, which act on thesecond component.

In that case the rolling bearing can be disposed on the sealed side inthe region of the gap between the two components or it can be arrangedon the non-sealed side of the gap. In the latter case the materials ofthe rolling bearing components are to be so selected as to be resistantin relation to the fluid.

The roiling bearing carries the forces which are carried by the plainbearing in the state of the art and can therefore substantially relievethe load on the plain bearing or even make it dispensable. The wear ofthe plain bearing is thereby greatly reduced or completely avoided. Evenin a situation involving high loadings due to high forces and highrelative speeds which occur over a long time between the two components,the rolling bearing itself is almost wear-free.

A particularly advantageous sealing system is one in which, on thepressure side of the seal, a plain bearing, in particular anaxial-radial plain bearing, is combined with a rolling bearing on thesealed side. That provides for a particularly advantageous sealingeffect and ensures that the forces between the two components arecarried in an advantageous manner.

An advantageous development of the sealing system provides that a thrustgroove-type ball bearing is selected as the rolling bearing.

The thrust groove-type ball bearing is particularly suitable for theusually cramped conditions as it is of a very compact form. In additionit is adapted to carry the forces which frequently occur predominantlyin the longitudinal direction of the bore in the first component, thatis to say the axial forces, between the first and second components.

A further advantageous embodiment of the sealing system according to theinvention includes a first component having a bore, a second componentwhich is arranged in the bore and a sealing ring of the above-describedkind which seals off the gap between the two components in relation to afluid which at least at times is under pressure.

In a particularly advantageous manner the sealing ring according to theinvention can be combined with a rolling bearing, as describedhereinbefore. That provides for particularly long-lived and reliablesealing of the gap between the first and second components.

Particularly in the case of sealing gaps which are in the form of acylindrical surface, the sealing system according to the inventionprovides a simple and effective sealing action.

Particularly preferred is the use of the sealing ring and sealing systemaccording to the invention for sealing the gap between an actuatingspindle of a ball valve and the housing of a ball valve.

The pressure of the fluid on the inside surface of the flow passageformed in the ball exerts a force on the ball, which is transmitted tothe actuating spindle fixed to the ball. In the case of the sealingsystem according to the invention, that force is advantageouslytransmitted to the housing of the ball valve from the actuating spindleby way of the rolling bearing. With the sealing system according to theinvention therefore, plain bearings which are possibly present and theseal itself are not subjected to the effect of those forces or they areonly slightly subjected thereto, and they are therefore substantiallyrelieved of stress. Wear of the seal and the plain bearing thereforedoes not occur or scarcely occurs.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

Preferred embodiments of the invention are described with reference tothe accompanying drawings in which:

FIG. 1 is a partially sectional side view of an embodiment of thesealing system according to the invention,

FIG. 2 is a partly sectional front view of a second embodiment of thesealing system according to the invention, and

FIG. 3 is a partly sectional front view of a third embodiment of thesealing system according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a housing 2 having a bore 4 in which an actuating spindleof a ball valve (not shown) is arranged. The gap between the actuatingspindle 6 and the housing 2 is sealed off by a sealing ring 8 with anoutside contour in the shape of a circular cylindrical tube.

The sealing ring 8 has an inwardly facing inner sealing surface 10 andan outwardly facing outer sealing surface 12. The radially inwardlyfacing sealing surface 10 bears against a radially outwardly facingsurface of the circular-cylindrical actuating spindle 6 and the radiallyoutwardly facing sealing surface 12 bears against a radially inwardlyfacing surface 14 of a groove 16 in the housing 2, in which the sealingring 8 is fitted.

A cavity 14 is provided in the sealing ring 8. The cavity is a groove inan axial outside surface 16 of the sealing ring 8. The groove 14 opensin the direction of a fluid 18 which is under pressure in the housing 2and which penetrates through the gap 4 between the actuating spindle 6and the wall of the bore 4 to the sealing ring 8 and there appliespressure to the cavity 14. The cavity 14 has a wall 20 which is of aparabolic configuration in cross-section. The wall 20, with respective‘limbs’ of the parabola, lies in radially opposite relationship torespective ones of the sealing surfaces 10, 12 and, being acted upon bythe pressure of the fluid 18, presses the sealing surfaces against thecomplementary sealing surfaces of the housing 2 and the actuatingspindle 6.

The actuating spindle 6 of the embodiment illustrated in FIG. 2 has afirst portion 6 a, a second portion 6 b and a third portion 6 c. Theportion 6 a is positively lockingly connected to the ball (not shown) ofthe ball valve, the ball being arranged in the cavity 30 in the housing2. The portion 6 b has a cylindrical surface 7, in relation to which thesealing surface 10 of the seal 8 seals.

Formed at the transition from the portion 6 a to the portion 6 b is astep having a surface 40 which is perpendicular to the longitudinaldirection of the actuating spindle 6. Also provided at the transitionfrom the portion 6 b to the portion 6 c is a step having a surface 41which is parallel to the surface 40.

The surface 40 of the first step is in contact with an annular plainbearing 50 arranged in the bore 4. The plain bearing 50 is in the formof a thrust-radial plain bearing and is supported in the region of astep in the bore 4 against the cylindrical outside surface and theannular end face of that step in the bore 4. The thrust-radial plainbearing is adapted to carry axial forces which are directed radiallyoutwardly in the flow passage 19 containing the fluid 18. For thatpurpose the surface 40 of the first step on the actuating spindle isremote from the flow passage 19 for the fluid 18 and the annular endface of the step of the bore 4 is towards the flow passage 19.

A first bearing shell 61 of a thrust groove-type ball bearing 60 issupported against the surface 41 of the second step on the actuatingspindle 6. The surface 41 faces away from the flow passage 19.

A second bearing shell 62 of the thrust groove-type ball bearing issupported against a housing portion 3 of the housing 2.

The balls of the groove-type ball bearing 60 are arranged between thefirst and second bearing shells 61, 62.

The upper end portion of the portion 6 c of the actuating spindle 6,like also in the case of the above-described embodiment, can be providedwith shaped surfaces such as for example square surfaces in order toapply a torque about the longitudinal axis of the actuating spindle 6 tothe actuating spindle.

The spacings of the surfaces 40 and 41 of the actuating spindle and theannular support surface in the step of the bore 4 and the supportsurface on the housing portion 3 which supports the second bearing shell62 are so selected that axially outwardly directed forces are passedfrom the actuating spindle 6 into the housing portion 3 by way of thegroove-type ball bearing 60 and transmission of those forces by way ofthe plain bearing 50 is substantially or completely avoided. In otherwords, the thrust groove-type ball bearing 60 and the plain bearing 50do not represent an overdefined bearing arrangement as the plain bearing50 has axial clearance.

The embodiment shown in FIG. 3 is identical to that shown in FIG. 2, inregard to the portions 6 a, 6 b of the actuating spindle 6, the plainbearing 50 and the seal 8.

The housing 2 of the embodiment in FIG. 3 has a flattened portion 5 atthe end of the bore 4, which is remote from the flow passage 19. Theflattened portion 5 is perpendicular to the longitudinal axis of thebore 4.

The annular surface 41 of the second step on the actuating spindle 6projects beyond the flattened portion 5 of the housing 2. Arranged onthe surface 41 is a plate 70 having an annular recess 71. The firstbearing shell 61 is arranged in the annular recess 71.

The groove-type ball bearing 60 projects axially beyond the annularrecess 71. The second bearing shell 62 of the groove-type ball bearing60 is arranged and supported in an annular recess 81 in a second plate80. The second plate 80 is connected to a housing portion 3.

In the embodiment in FIG. 3 the torque required for actuation of theactuating spindle 6 can be applied in the same manner as in theabove-discussed embodiments by way of shaped surfaces provided in theend region of the portion 6 c. Alternatively the torque required foractuation can be applied by way of the plate 70 if it is connected tothe actuating spindle 6 fixedly in respect of the transmission oftorque.

All of the above U.S. patents, U.S. patent application publications,U.S. patent applications, foreign patents, foreign patent applicationsand non-patent publications referred to in this specification and/orlisted in the Application Data Sheet, are incorporated herein byreference, in their entirety.

From the foregoing it will be appreciated that, although specificembodiments of the invention have been described herein for purposes ofillustration, various modifications may be made without deviating fromthe spirit and scope of the invention. Accordingly, the invention is notlimited except as by the appended claims.

1. A sealing ring for a ball valve of elastically deformable materialhaving a radially inwardly facing inner sealing surface and a radiallyoutwardly facing outer sealing surface, characterized by at least onepressure surface which as a wall of a cavity in the sealing ring is insubstantially radially opposite relationship to at least one of thesealing surfaces so that a fluid under pressure which bears in thecavity against the pressure surface urges at least one sealing surfaceoutwardly, wherein the cavity has an outwardly leading fluid opening. 2.A sealing ring according to claim 1 characterized in that the cavity isa groove in an axial outside surface of the sealing ring.
 3. A sealingring according to claim 1 characterized in that the sealing ring is inthe shape of a circular cylindrical tube.
 4. A sealing system comprisinga first component with a bore, a second component which is arranged inthe bore, and a sealing ring according to claim 1 for sealing the gapbetween the first and the second component in relation to a fluid whichat least at times is under pressure.
 5. A sealing system according toclaim 4 comprising a rolling bearing for carrying axial forces betweenthe first and second components.
 6. A sealing system according to claim5 characterized in that the rolling bearing is in the form of a thrustgroove-type ball bearing.
 7. A sealing system according to claim 5characterized in that the second component and the bore are of acircular-cylindrical configuration.
 8. A sealing system according toclaim 5 characterized in that the cavity has an opening for the fluidwhich is under pressure.
 9. A sealing system according to claim 4characterized in that the first component is a housing of a ball valveand the second component is the actuating spindle of a ball valve.
 10. Asealing system according to claim 9 characterized in that the rollingbearing is so arranged that it can carry forces which act axially inrelation to the actuating spindle and which are applied to the actuatingspindle by way of the fluid flowing through the ball of the ball valve.11. A sealing system according to claim 10 characterized in that a firstbearing shell of the rolling bearing is supported on a surface which isremote from the flow passage provided in the ball and which is connectedto the actuating spindle and a second bearing shell of the rollingbearing is supported on a surface which is towards the flow passage andwhich is connected to the housing.